Even though Halo 4 was the most polished game this year, I'd go for Dishonored. I believe the game has a lot of potential to grow even more!
Reach has the biggest environment models I've ever seen in a game. Yes, even bigger than God of War 3. And the technique they used to accomplish this was genius! (decrease foliage detail and expand the environment to HUGE sizes)
Scavenger6's comments